Effects of Scalp Nerve Block on Symptomatic Cerebral Hyperperfusion Syndrome After Combined Revascularization Surgery for Moyamoya Disease

Background: Strict blood pressure control can be used to prevent or treat cerebral hyperperfusion syndrome. This study investigated whether scalp nerve block (SNB) is associated with a reduced risk of postoperative symptomatic cerebral hyperperfusion syndrome (SCHS) by reducing postoperative blood pressure in adult patients who underwent combined revascularization surgery for moyamoya disease. Methods: Patients were retrospectively divided into the SNB (n=167) and control (n=221) groups depending on whether SNB was performed immediately before placement of wound dressings at the end of surgery. Postoperative SCHS was defined as new-onset postoperative neurological deficits with a focal increase in cerebral blood flow at the perianastomosis site in the absence of infarction or hemorrhage on postoperative brain imaging. Inverse probability of treatment weighting was used to balance preoperative variables between the 2 groups. Results: The incidence of postoperative SCHS did not differ between the SNB and control groups (61 [36.5%] vs. 102 [46.2%], P =0.072), but its duration was shorter in the SNB group (4 [2–6] vs. 5 [3–7] days, P =0.021). Although of limited clinical relevance, the SNB group had lower postoperative pain scores and systolic blood pressures at postoperative days 0 to 1 and a shorter intensive care unit stay. Conclusions: Despite some potential benefits, SNB was not associated with a reduced incidence of postoperative SCHS in adult patients who underwent combined revascularization surgery for moyamoya disease.